The present invention relates to a down converter and its control method, for example, to a down converter for down converting a received polarized wave signal and its control method.
There is known an LNB (Low Noise Block) down converter for converting a frequency of a received satellite broadcasting electric wave into an intermediate frequency (hereinafter, also called an IF frequency) that a receiver (e.g., tuner) can receive.
For example, Japanese Unexamined Patent Publication No. 2006-253885 discloses a receiver capable of receiving ground digital broadcasting and BS/CS broadcasting. The receiver described in Japanese Unexamined Patent Publication No. 2006-253885 has a local oscillation circuit for ground waves and a local oscillation circuit for BS/CS. Then, when the receiver is tuned to a BS/CS broadcasting wave, the receiver controls so that an oscillation frequency of the local oscillation circuit for ground waves may become a frequency that does not overlap frequency bands of the BS/CS broadcasting waves. This prevents deterioration of receiver performance.